DATA LOGGING ON HIGH DISCHARGE PRESSURES TRIPS

Working on behalf of the incumbent Chiller Maintenance Contractor, we were asked to compile an Investigative Report on the above Chiller Plant serving the Energy Centre’s recent High Pressure trips / operation.
To facilitate the investigation a Lap-top based dual unit Data Logger was fitted to Chiller No2 System No3. The first data logger used is a Pico ADC22 – 10 Bit Resolution split into 2 Conditioning Boards. The First Conditioning Board uses 11 Channels with installed OP Amps to piggy back the existing Micro-panel Transducer and Sensor Instrumentation; so not to impose an additional load to the control circuits. Each Channel has an Input Impedance of >10 MOhms. The second 11 Channel Condition Board has a 0.3 MOhms Input Impedance which is used to piggy back onto 0-10VDC Signals. The conditioning Boards were made by our Engineers and hold Calibration Certificates by from our Tool Calibration Company. The Second Data Logger is a Pico TC-08 – 10 Bit Resolution with 8 Input Channels suitable for K Thermocouples.
Chiller No2 System No3 was put into service and several events were captured both via the Data Logging and by visual inspection, these included:
• With an ambient of 7.0 DegC and a Return Water Temperature 10.0 DegC, System No3’s Discharge Pressure kept rising to above 16.0 BarG until the System Tripped on Low Discharge Superheat; R134a.
• The Discharge Superheat is VERY LOW at around 3 DegK which also suggests a refrigerant over-charge.
These findings were submitted along with the raw data collected.